ssh.c

   1 /*
   2  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   3  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   4  *                    All rights reserved
   5  * Ssh client program.  This program can be used to log into a remote machine.
   6  * The software supports strong authentication, encryption, and forwarding
   7  * of X11, TCP/IP, and authentication connections.
   8  *
   9  * As far as I am concerned, the code I have written for this software
  10  * can be used freely for any purpose.  Any derived versions of this
  11  * software must be clearly marked as such, and if the derived work is
  12  * incompatible with the protocol description in the RFC file, it must be
  13  * called by a name other than "ssh" or "Secure Shell".
  14  *
  15  * Copyright (c) 1999 Niels Provos.  All rights reserved.
  16  * Copyright (c) 2000, 2001, 2002, 2003 Markus Friedl.  All rights reserved.
  17  *
  18  * Modified to work with SSL by Niels Provos <provos@citi.umich.edu>
  19  * in Canada (German citizen).
  20  *
  21  * Redistribution and use in source and binary forms, with or without
  22  * modification, are permitted provided that the following conditions
  23  * are met:
  24  * 1. Redistributions of source code must retain the above copyright
  25  *    notice, this list of conditions and the following disclaimer.
  26  * 2. Redistributions in binary form must reproduce the above copyright
  27  *    notice, this list of conditions and the following disclaimer in the
  28  *    documentation and/or other materials provided with the distribution.
  29  *
  30  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  31  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  32  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  33  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  34  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  35  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  36  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  37  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  38  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  39  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  40  */
  41
  42 #include "includes.h"
  43 RCSID("$OpenBSD: ssh.c,v 1.208 2004/03/10 09:45:06 markus Exp $");
  44
  45 #include <openssl/evp.h>
  46 #include <openssl/err.h>
  47
  48 #include "ssh.h"
  49 #include "ssh1.h"
  50 #include "ssh2.h"
  51 #include "compat.h"
  52 #include "cipher.h"
  53 #include "xmalloc.h"
  54 #include "packet.h"
  55 #include "buffer.h"
  56 #include "channels.h"
  57 #include "key.h"
  58 #include "authfd.h"
  59 #include "authfile.h"
  60 #include "pathnames.h"
  61 #include "clientloop.h"
  62 #include "log.h"
  63 #include "readconf.h"
  64 #include "sshconnect.h"
  65 #include "tildexpand.h"
  66 #include "dispatch.h"
  67 #include "misc.h"
  68 #include "kex.h"
  69 #include "mac.h"
  70 #include "sshtty.h"
  71
  72 #ifdef SMARTCARD
  73 #include "scard.h"
  74 #endif
  75
  76 #ifdef HAVE___PROGNAME
  77 extern char *__progname;
  78 #else
  79 char *__progname;
  80 #endif
  81
  82 /* Flag indicating whether debug mode is on.  This can be set on the command line. */
  83 int debug_flag = 0;
  84
  85 /* Flag indicating whether a tty should be allocated */
  86 int tty_flag = 0;
  87 int no_tty_flag = 0;
  88 int force_tty_flag = 0;
  89
  90 /* don't exec a shell */
  91 int no_shell_flag = 0;
  92
  93 /*
  94  * Flag indicating that nothing should be read from stdin.  This can be set
  95  * on the command line.
  96  */
  97 int stdin_null_flag = 0;
  98
  99 /*
 100  * Flag indicating that ssh should fork after authentication.  This is useful
 101  * so that the passphrase can be entered manually, and then ssh goes to the
 102  * background.
 103  */
 104 int fork_after_authentication_flag = 0;
 105
 106 /*
 107  * General data structure for command line options and options configurable
 108  * in configuration files.  See readconf.h.
 109  */
 110 Options options;
 111
 112 /* optional user configfile */
 113 char *config = NULL;
 114
 115 /*
 116  * Name of the host we are connecting to.  This is the name given on the
 117  * command line, or the HostName specified for the user-supplied name in a
 118  * configuration file.
 119  */
 120 char *host;
 121
 122 /* socket address the host resolves to */
 123 struct sockaddr_storage hostaddr;
 124
 125 /* Private host keys. */
 126 Sensitive sensitive_data;
 127
 128 /* Original real UID. */
 129 uid_t original_real_uid;
 130 uid_t original_effective_uid;
 131
 132 /* command to be executed */
 133 Buffer command;
 134
 135 /* Should we execute a command or invoke a subsystem? */
 136 int subsystem_flag = 0;
 137
 138 /* # of replies received for global requests */
 139 static int client_global_request_id = 0;
 140
 141 /* pid of proxycommand child process */
 142 pid_t proxy_command_pid = 0;
 143
 144 /* Prints a help message to the user.  This function never returns. */
 145
 146 static void
 147 usage(void)
 148 {
 149         fprintf(stderr,
 150 "usage: ssh [-1246AaCfghkNnqsTtVvXxY] [-b bind_address] [-c cipher_spec]\n"
 151 "           [-D port] [-e escape_char] [-F configfile] [-i identity_file]\n"
 152 "           [-L port:host:hostport] [-l login_name] [-m mac_spec] [-o option]\n"
 153 "           [-p port] [-R port:host:hostport] [user@]hostname [command]\n"
 154         );
 155         exit(1);
 156 }
 157
 158 static int ssh_session(void);
 159 static int ssh_session2(void);
 160 static void load_public_identity_files(void);
 161
 162 /*
 163  * Main program for the ssh client.
 164  */
 165 int
 166 main(int ac, char **av)
 167 {
 168         int i, opt, exit_status;
 169         u_short fwd_port, fwd_host_port;
 170         char sfwd_port[6], sfwd_host_port[6];
 171         char *p, *cp, *line, buf[256];
 172         struct stat st;
 173         struct passwd *pw;
 174         int dummy;
 175         extern int optind, optreset;
 176         extern char *optarg;
 177
 178         __progname = ssh_get_progname(av[0]);
 179         init_rng();
 180
 181         /*
 182          * Save the original real uid.  It will be needed later (uid-swapping
 183          * may clobber the real uid).
 184          */
 185         original_real_uid = getuid();
 186         original_effective_uid = geteuid();
 187
 188         /*
 189          * Use uid-swapping to give up root privileges for the duration of
 190          * option processing.  We will re-instantiate the rights when we are
 191          * ready to create the privileged port, and will permanently drop
 192          * them when the port has been created (actually, when the connection
 193          * has been made, as we may need to create the port several times).
 194          */
 195         PRIV_END;
 196
 197 #ifdef HAVE_SETRLIMIT
 198         /* If we are installed setuid root be careful to not drop core. */
 199         if (original_real_uid != original_effective_uid) {
 200                 struct rlimit rlim;
 201                 rlim.rlim_cur = rlim.rlim_max = 0;
 202                 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
 203                         fatal("setrlimit failed: %.100s", strerror(errno));
 204         }
 205 #endif
 206         /* Get user data. */
 207         pw = getpwuid(original_real_uid);
 208         if (!pw) {
 209                 logit("You don't exist, go away!");
 210                 exit(1);
 211         }
 212         /* Take a copy of the returned structure. */
 213         pw = pwcopy(pw);
 214
 215         /*
 216          * Set our umask to something reasonable, as some files are created
 217          * with the default umask.  This will make them world-readable but
 218          * writable only by the owner, which is ok for all files for which we
 219          * don't set the modes explicitly.
 220          */
 221         umask(022);
 222
 223         /* Initialize option structure to indicate that no values have been set. */
 224         initialize_options(&options);
 225
 226         /* Parse command-line arguments. */
 227         host = NULL;
 228
 229 again:
 230         while ((opt = getopt(ac, av,
 231             "1246ab:c:e:fgi:kl:m:no:p:qstvxACD:F:I:L:NPR:TVXY")) != -1) {
 232                 switch (opt) {
 233                 case '1':
 234                         options.protocol = SSH_PROTO_1;
 235                         break;
 236                 case '2':
 237                         options.protocol = SSH_PROTO_2;
 238                         break;
 239                 case '4':
 240                         options.address_family = AF_INET;
 241                         break;
 242                 case '6':
 243                         options.address_family = AF_INET6;
 244                         break;
 245                 case 'n':
 246                         stdin_null_flag = 1;
 247                         break;
 248                 case 'f':
 249                         fork_after_authentication_flag = 1;
 250                         stdin_null_flag = 1;
 251                         break;
 252                 case 'x':
 253                         options.forward_x11 = 0;
 254                         break;
 255                 case 'X':
 256                         options.forward_x11 = 1;
 257                         break;
 258                 case 'Y':
 259                         options.forward_x11 = 1;
 260                         options.forward_x11_trusted = 1;
 261                         break;
 262                 case 'g':
 263                         options.gateway_ports = 1;
 264                         break;
 265                 case 'P':       /* deprecated */
 266                         options.use_privileged_port = 0;
 267                         break;
 268                 case 'a':
 269                         options.forward_agent = 0;
 270                         break;
 271                 case 'A':
 272                         options.forward_agent = 1;
 273                         break;
 274                 case 'k':
 275                         options.gss_deleg_creds = 0;
 276                         break;
 277                 case 'i':
 278                         if (stat(optarg, &st) < 0) {
 279                                 fprintf(stderr, "Warning: Identity file %s "
 280                                     "does not exist.\n", optarg);
 281                                 break;
 282                         }
 283                         if (options.num_identity_files >=
 284                             SSH_MAX_IDENTITY_FILES)
 285                                 fatal("Too many identity files specified "
 286                                     "(max %d)", SSH_MAX_IDENTITY_FILES);
 287                         options.identity_files[options.num_identity_files++] =
 288                             xstrdup(optarg);
 289                         break;
 290                 case 'I':
 291 #ifdef SMARTCARD
 292                         options.smartcard_device = xstrdup(optarg);
 293 #else
 294                         fprintf(stderr, "no support for smartcards.\n");
 295 #endif
 296                         break;
 297                 case 't':
 298                         if (tty_flag)
 299                                 force_tty_flag = 1;
 300                         tty_flag = 1;
 301                         break;
 302                 case 'v':
 303                         if (debug_flag == 0) {
 304                                 debug_flag = 1;
 305                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 306                         } else {
 307                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
 308                                         options.log_level++;
 309                                 break;
 310                         }
 311                         /* fallthrough */
 312                 case 'V':
 313                         fprintf(stderr,
 314                             "%s, SSH protocols %d.%d/%d.%d, %s\n",
 315                             SSH_VERSION,
 316                             PROTOCOL_MAJOR_1, PROTOCOL_MINOR_1,
 317                             PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2,
 318                             SSLeay_version(SSLEAY_VERSION));
 319                         if (opt == 'V')
 320                                 exit(0);
 321                         break;
 322                 case 'q':
 323                         options.log_level = SYSLOG_LEVEL_QUIET;
 324                         break;
 325                 case 'e':
 326                         if (optarg[0] == '^' && optarg[2] == 0 &&
 327                             (u_char) optarg[1] >= 64 &&
 328                             (u_char) optarg[1] < 128)
 329                                 options.escape_char = (u_char) optarg[1] & 31;
 330                         else if (strlen(optarg) == 1)
 331                                 options.escape_char = (u_char) optarg[0];
 332                         else if (strcmp(optarg, "none") == 0)
 333                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 334                         else {
 335                                 fprintf(stderr, "Bad escape character '%s'.\n",
 336                                     optarg);
 337                                 exit(1);
 338                         }
 339                         break;
 340                 case 'c':
 341                         if (ciphers_valid(optarg)) {
 342                                 /* SSH2 only */
 343                                 options.ciphers = xstrdup(optarg);
 344                                 options.cipher = SSH_CIPHER_ILLEGAL;
 345                         } else {
 346                                 /* SSH1 only */
 347                                 options.cipher = cipher_number(optarg);
 348                                 if (options.cipher == -1) {
 349                                         fprintf(stderr,
 350                                             "Unknown cipher type '%s'\n",
 351                                             optarg);
 352                                         exit(1);
 353                                 }
 354                                 if (options.cipher == SSH_CIPHER_3DES)
 355                                         options.ciphers = "3des-cbc";
 356                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 357                                         options.ciphers = "blowfish-cbc";
 358                                 else
 359                                         options.ciphers = (char *)-1;
 360                         }
 361                         break;
 362                 case 'm':
 363                         if (mac_valid(optarg))
 364                                 options.macs = xstrdup(optarg);
 365                         else {
 366                                 fprintf(stderr, "Unknown mac type '%s'\n",
 367                                     optarg);
 368                                 exit(1);
 369                         }
 370                         break;
 371                 case 'p':
 372                         options.port = a2port(optarg);
 373                         if (options.port == 0) {
 374                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 375                                 exit(1);
 376                         }
 377                         break;
 378                 case 'l':
 379                         options.user = optarg;
 380                         break;
 381
 382                 case 'L':
 383                 case 'R':
 384                         if (sscanf(optarg, "%5[0123456789]:%255[^:]:%5[0123456789]",
 385                             sfwd_port, buf, sfwd_host_port) != 3 &&
 386                             sscanf(optarg, "%5[0123456789]/%255[^/]/%5[0123456789]",
 387                             sfwd_port, buf, sfwd_host_port) != 3) {
 388                                 fprintf(stderr,
 389                                     "Bad forwarding specification '%s'\n",
 390                                     optarg);
 391                                 usage();
 392                                 /* NOTREACHED */
 393                         }
 394                         if ((fwd_port = a2port(sfwd_port)) == 0 ||
 395                             (fwd_host_port = a2port(sfwd_host_port)) == 0) {
 396                                 fprintf(stderr,
 397                                     "Bad forwarding port(s) '%s'\n", optarg);
 398                                 exit(1);
 399                         }
 400                         if (opt == 'L')
 401                                 add_local_forward(&options, fwd_port, buf,
 402                                     fwd_host_port);
 403                         else if (opt == 'R')
 404                                 add_remote_forward(&options, fwd_port, buf,
 405                                     fwd_host_port);
 406                         break;
 407
 408                 case 'D':
 409                         fwd_port = a2port(optarg);
 410                         if (fwd_port == 0) {
 411                                 fprintf(stderr, "Bad dynamic port '%s'\n",
 412                                     optarg);
 413                                 exit(1);
 414                         }
 415                         add_local_forward(&options, fwd_port, "socks", 0);
 416                         break;
 417
 418                 case 'C':
 419                         options.compression = 1;
 420                         break;
 421                 case 'N':
 422                         no_shell_flag = 1;
 423                         no_tty_flag = 1;
 424                         break;
 425                 case 'T':
 426                         no_tty_flag = 1;
 427                         break;
 428                 case 'o':
 429                         dummy = 1;
 430                         line = xstrdup(optarg);
 431                         if (process_config_line(&options, host ? host : "",
 432                             line, "command-line", 0, &dummy) != 0)
 433                                 exit(1);
 434                         xfree(line);
 435                         break;
 436                 case 's':
 437                         subsystem_flag = 1;
 438                         break;
 439                 case 'b':
 440                         options.bind_address = optarg;
 441                         break;
 442                 case 'F':
 443                         config = optarg;
 444                         break;
 445                 default:
 446                         usage();
 447                 }
 448         }
 449
 450         ac -= optind;
 451         av += optind;
 452
 453         if (ac > 0 && !host && **av != '-') {
 454                 if (strrchr(*av, '@')) {
 455                         p = xstrdup(*av);
 456                         cp = strrchr(p, '@');
 457                         if (cp == NULL || cp == p)
 458                                 usage();
 459                         options.user = p;
 460                         *cp = '\0';
 461                         host = ++cp;
 462                 } else
 463                         host = *av;
 464                 if (ac > 1) {
 465                         optind = optreset = 1;
 466                         goto again;
 467                 }
 468                 ac--, av++;
 469         }
 470
 471         /* Check that we got a host name. */
 472         if (!host)
 473                 usage();
 474
 475         SSLeay_add_all_algorithms();
 476         ERR_load_crypto_strings();
 477
 478         /* Initialize the command to execute on remote host. */
 479         buffer_init(&command);
 480
 481         /*
 482          * Save the command to execute on the remote host in a buffer. There
 483          * is no limit on the length of the command, except by the maximum
 484          * packet size.  Also sets the tty flag if there is no command.
 485          */
 486         if (!ac) {
 487                 /* No command specified - execute shell on a tty. */
 488                 tty_flag = 1;
 489                 if (subsystem_flag) {
 490                         fprintf(stderr,
 491                             "You must specify a subsystem to invoke.\n");
 492                         usage();
 493                 }
 494         } else {
 495                 /* A command has been specified.  Store it into the buffer. */
 496                 for (i = 0; i < ac; i++) {
 497                         if (i)
 498                                 buffer_append(&command, " ", 1);
 499                         buffer_append(&command, av[i], strlen(av[i]));
 500                 }
 501         }
 502
 503         /* Cannot fork to background if no command. */
 504         if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag)
 505                 fatal("Cannot fork into background without a command to execute.");
 506
 507         /* Allocate a tty by default if no command specified. */
 508         if (buffer_len(&command) == 0)
 509                 tty_flag = 1;
 510
 511         /* Force no tty */
 512         if (no_tty_flag)
 513                 tty_flag = 0;
 514         /* Do not allocate a tty if stdin is not a tty. */
 515         if (!isatty(fileno(stdin)) && !force_tty_flag) {
 516                 if (tty_flag)
 517                         logit("Pseudo-terminal will not be allocated because stdin is not a terminal.");
 518                 tty_flag = 0;
 519         }
 520
 521         /*
 522          * Initialize "log" output.  Since we are the client all output
 523          * actually goes to stderr.
 524          */
 525         log_init(av[0], options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 526             SYSLOG_FACILITY_USER, 1);
 527
 528         /*
 529          * Read per-user configuration file.  Ignore the system wide config
 530          * file if the user specifies a config file on the command line.
 531          */
 532         if (config != NULL) {
 533                 if (!read_config_file(config, host, &options))
 534                         fatal("Can't open user config file %.100s: "
 535                             "%.100s", config, strerror(errno));
 536         } else  {
 537                 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir,
 538                     _PATH_SSH_USER_CONFFILE);
 539                 (void)read_config_file(buf, host, &options);
 540
 541                 /* Read systemwide configuration file after use config. */
 542                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host, &options);
 543         }
 544
 545         /* Fill configuration defaults. */
 546         fill_default_options(&options);
 547
 548         channel_set_af(options.address_family);
 549
 550         /* reinit */
 551         log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 1);
 552
 553         seed_rng();
 554
 555         if (options.user == NULL)
 556                 options.user = xstrdup(pw->pw_name);
 557
 558         if (options.hostname != NULL)
 559                 host = options.hostname;
 560
 561         /* force lowercase for hostkey matching */
 562         if (options.host_key_alias != NULL) {
 563                 for (p = options.host_key_alias; *p; p++)
 564                         if (isupper(*p))
 565                                 *p = tolower(*p);
 566         }
 567
 568         if (options.proxy_command != NULL &&
 569             strcmp(options.proxy_command, "none") == 0)
 570                 options.proxy_command = NULL;
 571
 572         /* Open a connection to the remote host. */
 573         if (ssh_connect(host, &hostaddr, options.port,
 574             options.address_family, options.connection_attempts,
 575 #ifdef HAVE_CYGWIN
 576             options.use_privileged_port,
 577 #else
 578             original_effective_uid == 0 && options.use_privileged_port,
 579 #endif
 580             options.proxy_command) != 0)
 581                 exit(1);
 582
 583         /*
 584          * If we successfully made the connection, load the host private key
 585          * in case we will need it later for combined rsa-rhosts
 586          * authentication. This must be done before releasing extra
 587          * privileges, because the file is only readable by root.
 588          * If we cannot access the private keys, load the public keys
 589          * instead and try to execute the ssh-keysign helper instead.
 590          */
 591         sensitive_data.nkeys = 0;
 592         sensitive_data.keys = NULL;
 593         sensitive_data.external_keysign = 0;
 594         if (options.rhosts_rsa_authentication ||
 595             options.hostbased_authentication) {
 596                 sensitive_data.nkeys = 3;
 597                 sensitive_data.keys = xmalloc(sensitive_data.nkeys *
 598                     sizeof(Key));
 599
 600                 PRIV_START;
 601                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
 602                     _PATH_HOST_KEY_FILE, "", NULL);
 603                 sensitive_data.keys[1] = key_load_private_type(KEY_DSA,
 604                     _PATH_HOST_DSA_KEY_FILE, "", NULL);
 605                 sensitive_data.keys[2] = key_load_private_type(KEY_RSA,
 606                     _PATH_HOST_RSA_KEY_FILE, "", NULL);
 607                 PRIV_END;
 608
 609                 if (options.hostbased_authentication == 1 &&
 610                     sensitive_data.keys[0] == NULL &&
 611                     sensitive_data.keys[1] == NULL &&
 612                     sensitive_data.keys[2] == NULL) {
 613                         sensitive_data.keys[1] = key_load_public(
 614                             _PATH_HOST_DSA_KEY_FILE, NULL);
 615                         sensitive_data.keys[2] = key_load_public(
 616                             _PATH_HOST_RSA_KEY_FILE, NULL);
 617                         sensitive_data.external_keysign = 1;
 618                 }
 619         }
 620         /*
 621          * Get rid of any extra privileges that we may have.  We will no
 622          * longer need them.  Also, extra privileges could make it very hard
 623          * to read identity files and other non-world-readable files from the
 624          * user's home directory if it happens to be on a NFS volume where
 625          * root is mapped to nobody.
 626          */
 627         seteuid(original_real_uid);
 628         setuid(original_real_uid);
 629
 630         /*
 631          * Now that we are back to our own permissions, create ~/.ssh
 632          * directory if it doesn\'t already exist.
 633          */
 634         snprintf(buf, sizeof buf, "%.100s%s%.100s", pw->pw_dir, strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
 635         if (stat(buf, &st) < 0)
 636                 if (mkdir(buf, 0700) < 0)
 637                         error("Could not create directory '%.200s'.", buf);
 638
 639         /* load options.identity_files */
 640         load_public_identity_files();
 641
 642         /* Expand ~ in known host file names. */
 643         /* XXX mem-leaks: */
 644         options.system_hostfile =
 645             tilde_expand_filename(options.system_hostfile, original_real_uid);
 646         options.user_hostfile =
 647             tilde_expand_filename(options.user_hostfile, original_real_uid);
 648         options.system_hostfile2 =
 649             tilde_expand_filename(options.system_hostfile2, original_real_uid);
 650         options.user_hostfile2 =
 651             tilde_expand_filename(options.user_hostfile2, original_real_uid);
 652
 653         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
 654
 655         /* Log into the remote system.  This never returns if the login fails. */
 656         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr, pw);
 657
 658         /* We no longer need the private host keys.  Clear them now. */
 659         if (sensitive_data.nkeys != 0) {
 660                 for (i = 0; i < sensitive_data.nkeys; i++) {
 661                         if (sensitive_data.keys[i] != NULL) {
 662                                 /* Destroys contents safely */
 663                                 debug3("clear hostkey %d", i);
 664                                 key_free(sensitive_data.keys[i]);
 665                                 sensitive_data.keys[i] = NULL;
 666                         }
 667                 }
 668                 xfree(sensitive_data.keys);
 669         }
 670         for (i = 0; i < options.num_identity_files; i++) {
 671                 if (options.identity_files[i]) {
 672                         xfree(options.identity_files[i]);
 673                         options.identity_files[i] = NULL;
 674                 }
 675                 if (options.identity_keys[i]) {
 676                         key_free(options.identity_keys[i]);
 677                         options.identity_keys[i] = NULL;
 678                 }
 679         }
 680
 681         exit_status = compat20 ? ssh_session2() : ssh_session();
 682         packet_close();
 683
 684         /*
 685          * Send SIGHUP to proxy command if used. We don't wait() in
 686          * case it hangs and instead rely on init to reap the child
 687          */
 688         if (proxy_command_pid > 1)
 689                 kill(proxy_command_pid, SIGHUP);
 690
 691         return exit_status;
 692 }
 693
 694 #define SSH_X11_PROTO "MIT-MAGIC-COOKIE-1"
 695
 696 static void
 697 x11_get_proto(char **_proto, char **_data)
 698 {
 699         char cmd[1024];
 700         char line[512];
 701         char xdisplay[512];
 702         static char proto[512], data[512];
 703         FILE *f;
 704         int got_data = 0, generated = 0, do_unlink = 0, i;
 705         char *display, *xauthdir, *xauthfile;
 706         struct stat st;
 707
 708         xauthdir = xauthfile = NULL;
 709         *_proto = proto;
 710         *_data = data;
 711         proto[0] = data[0] = '\0';
 712
 713         if (!options.xauth_location ||
 714             (stat(options.xauth_location, &st) == -1)) {
 715                 debug("No xauth program.");
 716         } else {
 717                 if ((display = getenv("DISPLAY")) == NULL) {
 718                         debug("x11_get_proto: DISPLAY not set");
 719                         return;
 720                 }
 721                 /*
 722                  * Handle FamilyLocal case where $DISPLAY does
 723                  * not match an authorization entry.  For this we
 724                  * just try "xauth list unix:displaynum.screennum".
 725                  * XXX: "localhost" match to determine FamilyLocal
 726                  *      is not perfect.
 727                  */
 728                 if (strncmp(display, "localhost:", 10) == 0) {
 729                         snprintf(xdisplay, sizeof(xdisplay), "unix:%s",
 730                             display + 10);
 731                         display = xdisplay;
 732                 }
 733                 if (options.forward_x11_trusted == 0) {
 734                         xauthdir = xmalloc(MAXPATHLEN);
 735                         xauthfile = xmalloc(MAXPATHLEN);
 736                         strlcpy(xauthdir, "/tmp/ssh-XXXXXXXXXX", MAXPATHLEN);
 737                         if (mkdtemp(xauthdir) != NULL) {
 738                                 do_unlink = 1;
 739                                 snprintf(xauthfile, MAXPATHLEN, "%s/xauthfile",
 740                                     xauthdir);
 741                                 snprintf(cmd, sizeof(cmd),
 742                                     "%s -f %s generate %s " SSH_X11_PROTO
 743                                     " untrusted timeout 1200 2>" _PATH_DEVNULL,
 744                                     options.xauth_location, xauthfile, display);
 745                                 debug2("x11_get_proto: %s", cmd);
 746                                 if (system(cmd) == 0)
 747                                         generated = 1;
 748                         }
 749                 }
 750                 snprintf(cmd, sizeof(cmd),
 751                     "%s %s%s list %s . 2>" _PATH_DEVNULL,
 752                     options.xauth_location,
 753                     generated ? "-f " : "" ,
 754                     generated ? xauthfile : "",
 755                     display);
 756                 debug2("x11_get_proto: %s", cmd);
 757                 f = popen(cmd, "r");
 758                 if (f && fgets(line, sizeof(line), f) &&
 759                     sscanf(line, "%*s %511s %511s", proto, data) == 2)
 760                         got_data = 1;
 761                 if (f)
 762                         pclose(f);
 763         }
 764
 765         if (do_unlink) {
 766                 unlink(xauthfile);
 767                 rmdir(xauthdir);
 768         }
 769         if (xauthdir)
 770                 xfree(xauthdir);
 771         if (xauthfile)
 772                 xfree(xauthfile);
 773
 774         /*
 775          * If we didn't get authentication data, just make up some
 776          * data.  The forwarding code will check the validity of the
 777          * response anyway, and substitute this data.  The X11
 778          * server, however, will ignore this fake data and use
 779          * whatever authentication mechanisms it was using otherwise
 780          * for the local connection.
 781          */
 782         if (!got_data) {
 783                 u_int32_t rand = 0;
 784
 785                 logit("Warning: No xauth data; "
 786                     "using fake authentication data for X11 forwarding.");
 787                 strlcpy(proto, SSH_X11_PROTO, sizeof proto);
 788                 for (i = 0; i < 16; i++) {
 789                         if (i % 4 == 0)
 790                                 rand = arc4random();
 791                         snprintf(data + 2 * i, sizeof data - 2 * i, "%02x",
 792                             rand & 0xff);
 793                         rand >>= 8;
 794                 }
 795         }
 796 }
 797
 798 static void
 799 ssh_init_forwarding(void)
 800 {
 801         int success = 0;
 802         int i;
 803
 804         /* Initiate local TCP/IP port forwardings. */
 805         for (i = 0; i < options.num_local_forwards; i++) {
 806                 debug("Connections to local port %d forwarded to remote address %.200s:%d",
 807                     options.local_forwards[i].port,
 808                     options.local_forwards[i].host,
 809                     options.local_forwards[i].host_port);
 810                 success += channel_setup_local_fwd_listener(
 811                     options.local_forwards[i].port,
 812                     options.local_forwards[i].host,
 813                     options.local_forwards[i].host_port,
 814                     options.gateway_ports);
 815         }
 816         if (i > 0 && success == 0)
 817                 error("Could not request local forwarding.");
 818
 819         /* Initiate remote TCP/IP port forwardings. */
 820         for (i = 0; i < options.num_remote_forwards; i++) {
 821                 debug("Connections to remote port %d forwarded to local address %.200s:%d",
 822                     options.remote_forwards[i].port,
 823                     options.remote_forwards[i].host,
 824                     options.remote_forwards[i].host_port);
 825                 channel_request_remote_forwarding(
 826                     options.remote_forwards[i].port,
 827                     options.remote_forwards[i].host,
 828                     options.remote_forwards[i].host_port);
 829         }
 830 }
 831
 832 static void
 833 check_agent_present(void)
 834 {
 835         if (options.forward_agent) {
 836                 /* Clear agent forwarding if we don\'t have an agent. */
 837                 if (!ssh_agent_present())
 838                         options.forward_agent = 0;
 839         }
 840 }
 841
 842 static int
 843 ssh_session(void)
 844 {
 845         int type;
 846         int interactive = 0;
 847         int have_tty = 0;
 848         struct winsize ws;
 849         char *cp;
 850
 851         /* Enable compression if requested. */
 852         if (options.compression) {
 853                 debug("Requesting compression at level %d.", options.compression_level);
 854
 855                 if (options.compression_level < 1 || options.compression_level > 9)
 856                         fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
 857
 858                 /* Send the request. */
 859                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
 860                 packet_put_int(options.compression_level);
 861                 packet_send();
 862                 packet_write_wait();
 863                 type = packet_read();
 864                 if (type == SSH_SMSG_SUCCESS)
 865                         packet_start_compression(options.compression_level);
 866                 else if (type == SSH_SMSG_FAILURE)
 867                         logit("Warning: Remote host refused compression.");
 868                 else
 869                         packet_disconnect("Protocol error waiting for compression response.");
 870         }
 871         /* Allocate a pseudo tty if appropriate. */
 872         if (tty_flag) {
 873                 debug("Requesting pty.");
 874
 875                 /* Start the packet. */
 876                 packet_start(SSH_CMSG_REQUEST_PTY);
 877
 878                 /* Store TERM in the packet.  There is no limit on the
 879                    length of the string. */
 880                 cp = getenv("TERM");
 881                 if (!cp)
 882                         cp = "";
 883                 packet_put_cstring(cp);
 884
 885                 /* Store window size in the packet. */
 886                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
 887                         memset(&ws, 0, sizeof(ws));
 888                 packet_put_int(ws.ws_row);
 889                 packet_put_int(ws.ws_col);
 890                 packet_put_int(ws.ws_xpixel);
 891                 packet_put_int(ws.ws_ypixel);
 892
 893                 /* Store tty modes in the packet. */
 894                 tty_make_modes(fileno(stdin), NULL);
 895
 896                 /* Send the packet, and wait for it to leave. */
 897                 packet_send();
 898                 packet_write_wait();
 899
 900                 /* Read response from the server. */
 901                 type = packet_read();
 902                 if (type == SSH_SMSG_SUCCESS) {
 903                         interactive = 1;
 904                         have_tty = 1;
 905                 } else if (type == SSH_SMSG_FAILURE)
 906                         logit("Warning: Remote host failed or refused to allocate a pseudo tty.");
 907                 else
 908                         packet_disconnect("Protocol error waiting for pty request response.");
 909         }
 910         /* Request X11 forwarding if enabled and DISPLAY is set. */
 911         if (options.forward_x11 && getenv("DISPLAY") != NULL) {
 912                 char *proto, *data;
 913                 /* Get reasonable local authentication information. */
 914                 x11_get_proto(&proto, &data);
 915                 /* Request forwarding with authentication spoofing. */
 916                 debug("Requesting X11 forwarding with authentication spoofing.");
 917                 x11_request_forwarding_with_spoofing(0, proto, data);
 918
 919                 /* Read response from the server. */
 920                 type = packet_read();
 921                 if (type == SSH_SMSG_SUCCESS) {
 922                         interactive = 1;
 923                 } else if (type == SSH_SMSG_FAILURE) {
 924                         logit("Warning: Remote host denied X11 forwarding.");
 925                 } else {
 926                         packet_disconnect("Protocol error waiting for X11 forwarding");
 927                 }
 928         }
 929         /* Tell the packet module whether this is an interactive session. */
 930         packet_set_interactive(interactive);
 931
 932         /* Request authentication agent forwarding if appropriate. */
 933         check_agent_present();
 934
 935         if (options.forward_agent) {
 936                 debug("Requesting authentication agent forwarding.");
 937                 auth_request_forwarding();
 938
 939                 /* Read response from the server. */
 940                 type = packet_read();
 941                 packet_check_eom();
 942                 if (type != SSH_SMSG_SUCCESS)
 943                         logit("Warning: Remote host denied authentication agent forwarding.");
 944         }
 945
 946         /* Initiate port forwardings. */
 947         ssh_init_forwarding();
 948
 949         /* If requested, let ssh continue in the background. */
 950         if (fork_after_authentication_flag)
 951                 if (daemon(1, 1) < 0)
 952                         fatal("daemon() failed: %.200s", strerror(errno));
 953
 954         /*
 955          * If a command was specified on the command line, execute the
 956          * command now. Otherwise request the server to start a shell.
 957          */
 958         if (buffer_len(&command) > 0) {
 959                 int len = buffer_len(&command);
 960                 if (len > 900)
 961                         len = 900;
 962                 debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
 963                 packet_start(SSH_CMSG_EXEC_CMD);
 964                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
 965                 packet_send();
 966                 packet_write_wait();
 967         } else {
 968                 debug("Requesting shell.");
 969                 packet_start(SSH_CMSG_EXEC_SHELL);
 970                 packet_send();
 971                 packet_write_wait();
 972         }
 973
 974         /* Enter the interactive session. */
 975         return client_loop(have_tty, tty_flag ?
 976             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
 977 }
 978
 979 static void
 980 client_subsystem_reply(int type, u_int32_t seq, void *ctxt)
 981 {
 982         int id, len;
 983
 984         id = packet_get_int();
 985         len = buffer_len(&command);
 986         if (len > 900)
 987                 len = 900;
 988         packet_check_eom();
 989         if (type == SSH2_MSG_CHANNEL_FAILURE)
 990                 fatal("Request for subsystem '%.*s' failed on channel %d",
 991                     len, (u_char *)buffer_ptr(&command), id);
 992 }
 993
 994 void
 995 client_global_request_reply_fwd(int type, u_int32_t seq, void *ctxt)
 996 {
 997         int i;
 998
 999         i = client_global_request_id++;
1000         if (i >= options.num_remote_forwards)
1001                 return;
1002         debug("remote forward %s for: listen %d, connect %s:%d",
1003             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1004             options.remote_forwards[i].port,
1005             options.remote_forwards[i].host,
1006             options.remote_forwards[i].host_port);
1007         if (type == SSH2_MSG_REQUEST_FAILURE)
1008                 logit("Warning: remote port forwarding failed for listen port %d",
1009                     options.remote_forwards[i].port);
1010 }
1011
1012 /* request pty/x11/agent/tcpfwd/shell for channel */
1013 static void
1014 ssh_session2_setup(int id, void *arg)
1015 {
1016         int len;
1017         int interactive = 0;
1018         struct termios tio;
1019
1020         debug2("ssh_session2_setup: id %d", id);
1021
1022         if (tty_flag) {
1023                 struct winsize ws;
1024                 char *cp;
1025                 cp = getenv("TERM");
1026                 if (!cp)
1027                         cp = "";
1028                 /* Store window size in the packet. */
1029                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
1030                         memset(&ws, 0, sizeof(ws));
1031
1032                 channel_request_start(id, "pty-req", 0);
1033                 packet_put_cstring(cp);
1034                 packet_put_int(ws.ws_col);
1035                 packet_put_int(ws.ws_row);
1036                 packet_put_int(ws.ws_xpixel);
1037                 packet_put_int(ws.ws_ypixel);
1038                 tio = get_saved_tio();
1039                 tty_make_modes(/*ignored*/ 0, &tio);
1040                 packet_send();
1041                 interactive = 1;
1042                 /* XXX wait for reply */
1043         }
1044         if (options.forward_x11 &&
1045             getenv("DISPLAY") != NULL) {
1046                 char *proto, *data;
1047                 /* Get reasonable local authentication information. */
1048                 x11_get_proto(&proto, &data);
1049                 /* Request forwarding with authentication spoofing. */
1050                 debug("Requesting X11 forwarding with authentication spoofing.");
1051                 x11_request_forwarding_with_spoofing(id, proto, data);
1052                 interactive = 1;
1053                 /* XXX wait for reply */
1054         }
1055
1056         check_agent_present();
1057         if (options.forward_agent) {
1058                 debug("Requesting authentication agent forwarding.");
1059                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1060                 packet_send();
1061         }
1062
1063         len = buffer_len(&command);
1064         if (len > 0) {
1065                 if (len > 900)
1066                         len = 900;
1067                 if (subsystem_flag) {
1068                         debug("Sending subsystem: %.*s", len, (u_char *)buffer_ptr(&command));
1069                         channel_request_start(id, "subsystem", /*want reply*/ 1);
1070                         /* register callback for reply */
1071                         /* XXX we assume that client_loop has already been called */
1072                         dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &client_subsystem_reply);
1073                         dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &client_subsystem_reply);
1074                 } else {
1075                         debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
1076                         channel_request_start(id, "exec", 0);
1077                 }
1078                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1079                 packet_send();
1080         } else {
1081                 channel_request_start(id, "shell", 0);
1082                 packet_send();
1083         }
1084
1085         packet_set_interactive(interactive);
1086 }
1087
1088 /* open new channel for a session */
1089 static int
1090 ssh_session2_open(void)
1091 {
1092         Channel *c;
1093         int window, packetmax, in, out, err;
1094
1095         if (stdin_null_flag) {
1096                 in = open(_PATH_DEVNULL, O_RDONLY);
1097         } else {
1098                 in = dup(STDIN_FILENO);
1099         }
1100         out = dup(STDOUT_FILENO);
1101         err = dup(STDERR_FILENO);
1102
1103         if (in < 0 || out < 0 || err < 0)
1104                 fatal("dup() in/out/err failed");
1105
1106         /* enable nonblocking unless tty */
1107         if (!isatty(in))
1108                 set_nonblock(in);
1109         if (!isatty(out))
1110                 set_nonblock(out);
1111         if (!isatty(err))
1112                 set_nonblock(err);
1113
1114         window = CHAN_SES_WINDOW_DEFAULT;
1115         packetmax = CHAN_SES_PACKET_DEFAULT;
1116         if (tty_flag) {
1117                 window >>= 1;
1118                 packetmax >>= 1;
1119         }
1120         c = channel_new(
1121             "session", SSH_CHANNEL_OPENING, in, out, err,
1122             window, packetmax, CHAN_EXTENDED_WRITE,
1123             "client-session", /*nonblock*/0);
1124
1125         debug3("ssh_session2_open: channel_new: %d", c->self);
1126
1127         channel_send_open(c->self);
1128         if (!no_shell_flag)
1129                 channel_register_confirm(c->self, ssh_session2_setup);
1130
1131         return c->self;
1132 }
1133
1134 static int
1135 ssh_session2(void)
1136 {
1137         int id = -1;
1138
1139         /* XXX should be pre-session */
1140         ssh_init_forwarding();
1141
1142         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1143                 id = ssh_session2_open();
1144
1145         /* If requested, let ssh continue in the background. */
1146         if (fork_after_authentication_flag)
1147                 if (daemon(1, 1) < 0)
1148                         fatal("daemon() failed: %.200s", strerror(errno));
1149
1150         return client_loop(tty_flag, tty_flag ?
1151             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1152 }
1153
1154 static void
1155 load_public_identity_files(void)
1156 {
1157         char *filename;
1158         int i = 0;
1159         Key *public;
1160 #ifdef SMARTCARD
1161         Key **keys;
1162
1163         if (options.smartcard_device != NULL &&
1164             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1165             (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL ) {
1166                 int count = 0;
1167                 for (i = 0; keys[i] != NULL; i++) {
1168                         count++;
1169                         memmove(&options.identity_files[1], &options.identity_files[0],
1170                             sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1));
1171                         memmove(&options.identity_keys[1], &options.identity_keys[0],
1172                             sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1));
1173                         options.num_identity_files++;
1174                         options.identity_keys[0] = keys[i];
1175                         options.identity_files[0] = sc_get_key_label(keys[i]);
1176                 }
1177                 if (options.num_identity_files > SSH_MAX_IDENTITY_FILES)
1178                         options.num_identity_files = SSH_MAX_IDENTITY_FILES;
1179                 i = count;
1180                 xfree(keys);
1181         }
1182 #endif /* SMARTCARD */
1183         for (; i < options.num_identity_files; i++) {
1184                 filename = tilde_expand_filename(options.identity_files[i],
1185                     original_real_uid);
1186                 public = key_load_public(filename, NULL);
1187                 debug("identity file %s type %d", filename,
1188                     public ? public->type : -1);
1189                 xfree(options.identity_files[i]);
1190                 options.identity_files[i] = filename;
1191                 options.identity_keys[i] = public;
1192         }
1193 }